Chris Brown / Drake Fight -- Nightclub Surveillance Tape Pretty Much Useless

Police are currently in possession of nightclub surveillance footage from the Chris Brown/Drake melee early Thursday AM -- but TMZ has learned, the footage is so dark ... the tape's basically worthless.

Law enforcement sources tell us, the club voluntarily handed over the surveillance footage yesterday.

But it won't do much good anyway -- we're told it's nearly impossible to make out faces on the footage because the club was so dark when the fight broke out.